News » Mike Kotschenreutherhttp://www.utexas.edu/news/
The University of Texas at AustinTue, 03 Mar 2015 23:05:09 +0000enhourly1http://wordpress.org/?v=3.2.1Nuclear Waste-Burning Technology Could Change the Face of Nuclear Energyhttp://www.utexas.edu/news/2012/09/12/nuclear-waste-burning-technology-change-face-of-nuclear-energy/
http://www.utexas.edu/news/2012/09/12/nuclear-waste-burning-technology-change-face-of-nuclear-energy/#commentsWed, 12 Sep 2012 14:35:16 +0000Lee Clippardhttp://www.utexas.edu/news/2012/09/10/University of Texas at Austin physicists have been awarded a U.S. patent for an invention that could someday be used to turn nuclear waste into fuel, thus removing the most dangerous forms of waste from the fuel cycle.

The researchers — Mike Kotschenreuther, Prashant Valanju and Swadesh Mahajan of the College of Natural Sciences — have patented the concept for a novel fusion-fission hybrid nuclear reactor that would use nuclear fusion and fission together to incinerate nuclear waste. Fusion produces energy by fusing atomic nuclei, and fission produces energy by splitting atomic nuclei.

The process of burning the waste would also produce energy. The researchers’ goal is to eliminate 99 percent of the most toxic transuranic waste from nuclear fission reactors.

“The potential for this kind of technology is enormous,” said Mahajan, professor of physics. “Now that we have the patent, we hope this will open up opportunities to engage with the research and development community to further this potentially world-changing technology.”

The researchers’ patent covers a tokamak device, which uses magnetic fields to produce fusion reactions. The patented tokamak is surrounded by an area that would house a nuclear waste fuel source and waste by-products of the nuclear fuel cycle. The device is driven by a transformational technology called the Super X Divertor.

The Super X Divertor is a crucial technology that has the capacity to safely divert the enormous amounts of heat out of the reactor core to keep the reactor producing energy.

Toxic nuclear waste is stored at sites around the U.S., and the need to store nuclear waste is widely considered to be a major disadvantage associated with nuclear energy.

The physicists’ invention could someday drastically decrease the need for any additional or expanded geological repositories, making nuclear power cleaner and more viable.

The patented hybrid reactor is currently in a conceptual phase.

The Super X Divertor, however, is being installed as the centerpiece of a $40 million upgrade of the MAST tokamak in the United Kingdom. This installation is a critical step forward in testing the Super X Divertor experimentally. It is not covered by the U.S. patent but is the technology invented by the University of Texas at Austin physicists.

]]>http://www.utexas.edu/news/2012/09/12/nuclear-waste-burning-technology-change-face-of-nuclear-energy/feed/537154nuclear-waste-burning-technology-change-face-of-nuclear-energynuclear-waste-burning-technology-change-face-of-nuclear-energy2012Nuclear Fusion-Fission Hybrid Could Destroy Nuclear Waste and Contribute to Carbon-Free Energy Futurehttp://www.utexas.edu/news/2009/01/27/nuclear_hybrid/
http://www.utexas.edu/news/2009/01/27/nuclear_hybrid/#commentsTue, 27 Jan 2009 20:37:10 +0000Lee Clippardhttp://www.utexas.edu/news/?p=3809» Continue Reading]]>Physicists at The University of Texas at Austin have designed a new system that, when fully developed, would use fusion to eliminate most of the transuranic waste produced by nuclear power plants.

The invention could help combat global warming by making nuclear power cleaner and thus a more viable replacement of carbon-heavy energy sources, such as coal.

The idea behind the compact Fusion-Fission Hybrid is that fusion can be used to burn nuclear waste, producing energy and getting rid of much of the long-lived waste generated by nuclear reactors.

View the complete illustration of the new nuclear waste destruction system, demonstrating how a fusion-fission hybrid, made possible by the Super X Divertor invented by University of Texas at Austin physicists, could integrate into the nuclear fuel cycle. (Large image opens in a new window.)Illustration: Angela Wong

"We have created a way to use fusion to relatively inexpensively destroy the waste from nuclear fission," says Mike Kotschenreuther, senior research scientist with the Institute for Fusion Studies (IFS) and Department of Physics. "Our waste destruction system, we believe, will allow nuclear power—a low carbon source of energy—to take its place in helping us combat global warming."

Toxic nuclear waste is stored at sites around the U.S. Debate surrounds the construction of a large-scale geological storage site at Yucca Mountain in Nevada, which many maintain is costly and dangerous. The storage capacity of Yucca Mountain, which is not expected to open until 2020, is set at 77,000 tons. The amount of nuclear waste generated by the U.S. will exceed this amount by 2010.

The physicists' new invention could drastically decrease the need for any additional or expanded geological repositories.

"Most people cite nuclear waste as the main reason they oppose nuclear fission as a source of power," says Swadesh Mahajan, senior research scientist.

The scientists propose destroying the waste using a fusion-fission hybrid reactor, the centerpiece of which is a high power Compact Fusion Neutron Source (CFNS) made possible by a crucial invention.

The CFNS would provide abundant neutrons through fusion to a surrounding fission blanket that uses transuranic waste as nuclear fuel. The fusion-produced neutrons augment the fission reaction, imparting efficiency and stability to the waste incineration process.

Kotschenreuther, Mahajan and Prashant Valanju, of the IFS, and Erich Schneider of the Department of Mechanical Engineering report their new system for nuclear waste destruction in the journal Fusion Engineering and Design.

There are more than 100 fission reactors, called "light water reactors" (LWRs), producing power in the United States. The nuclear waste from these reactors is stored and not reprocessed. (Some other countries, such as France and Japan, do reprocess the waste.)

The scientists' waste destruction system would work in two major steps.

First, 75 percent of the original reactor waste is destroyed in standard, relatively inexpensive LWRs. This step produces energy, but it does not destroy highly radiotoxic, transuranic, long-lived waste, what the scientists call "sludge."

In the second step, the sludge would be destroyed in a CFNS-based fusion-fission hybrid. The hybrid's potential lies in its ability to burn this hazardous sludge, which cannot be stably burnt in conventional systems.

"To burn this really hard to burn sludge, you really need to hit it with a sledgehammer, and that's what we have invented here," says Kotschenreuther.

One hybrid would be needed to destroy the waste produced by 10 to 15 LWRs.

The process would ultimately reduce the transuranic waste from the original fission reactors by up to 99 percent. Burning that waste also produces energy.

The CFNS is designed to be no larger than a small room, and much fewer of the devices would be needed compared to other schemes that are being investigated for similar processes. In combination with the substantial decrease in the need for geological storage, the CFNS-enabled waste-destruction system would be much cheaper and faster than other routes, say the scientists.

The CFNS is based on a tokamak, which is a machine with a "magnetic bottle" that is highly successful in confining high temperature (more than 100 million degrees Celsius) fusion plasmas for sufficiently long times.

The crucial invention that would pave the way for a CFNS is called the Super X Divertor. The Super X Divertor is designed to handle the enormous heat and particle fluxes peculiar to compact devices; it would enable the CFNS to safely produce large amounts of neutrons without destroying the system.

"The intense heat generated in a nuclear fusion device can literally destroy the walls of the machine," says research scientist Valanju, "and that is the thing that has been holding back a highly compact source of nuclear fusion."

Valanju says a fusion-fission hybrid reactor has been an idea in the physics community for a long time.

"It's always been known that fusion is good at producing neutrons and fission is good at making energy," he says. "Now, we have shown that we can get fusion to produce a lot of neutrons in a small space."

Producing an abundant and clean source of "pure fusion energy" continues to be a goal for fusion researchers. But the physicists say that harnessing the other product of fusion—neutrons—can be achieved in the near term.

In moving their hybrid from concept into production, the scientists hope to make nuclear energy a more viable alternative to coal and oil while waiting for renewables like solar and pure fusion to ramp up.

"The hybrid we designed should be viewed as a bridge technology," says Mahajan. "Through the hybrid, we can bring fusion via neutrons to the service of the energy sector today. We can hopefully make a major contribution to the carbon-free mix dictated by the 2050 time scale set by global warming scientists."

The scientists say their Super X Divertor invention has already gained acceptance in the fusion community. Several groups are considering implemented the Super X Divertor on their machines, including the MAST tokamak in the United Kingdom, and the DIIID (General Atomics) and NSTX (Princeton University) in the U.S. Next steps will include performing extended simulations, transforming the concept into an engineering project, and seeking funding for building a prototype.